Recently numbers of cars employ an electronic governor, which detects a steered amount of angular rotation of the steering wheel with an angle sensor, thereby controlling the brake, suspension and accelerator at, e.g., a sharp curve, for safe driving.
Some angle sensors have two gears rotating along with steering and having phase difference each other, and detect the amount of angular rotation of steering from the angle of the two gears. However, such kinds of sensor might have error of the angle of the two gears because of backlash. Especially it might occur at the start of rotating, and complicated calculation is necessary to obtain the amount of angular rotation of steering.
More over, even those problems might be solved, if the angle sensor is detached from the car for, e.g., repairing, the angle sensor should be remounted at the right place, otherwise, it misleads a driver instead of contributing to the safe driving. To be more specific, there are following problems in detaching and remounting the angle sensor.
Before the angle sensor is detached from the car, the sensor indicates data of a turned angle data (steered angle data) responsive to the status of the tire with respect to the car body. Once the angle sensor is detached from the car, and if the sensor is re-mounted to the car with some deviation by mistake, the steered angle data obtained after the re-mounting differs from the data obtained before the detachment of the sensor. However, the electronic governor of the car controls various items based on this wrong “steered angle data”. In this case, since a status of the tire with respect to the car body does not match the steered angle data, the angle sensor misleads the driver instead of aiding the driver in driving safely.